Circuits reside in many electronic products to perform specific operations. Variations in parameters such as fabricating process, voltage, and temperature may affect operations of such circuits. Designers often analyze (e.g., by simulation) these circuits at different operating conditions (e.g., different voltages, temperatures, or both) to ensure circuit operations meet design specifications. Inaccurate analysis of these circuits may lead to inferior products or may cause product operational failures at some operating conditions.